Fully Enclosed Composite Micro/Nano‐Package for High‐Quality Micro‐LED Display Pixels and In Situ Nanoimprint Technology

Abstract

AbstractMicro/mini‐light emitting diode (LED) arrays are regarded as the most promising next generation of display devices. However, the inherent Lambertian radiation of LED chips results in a significant pixel crosstalk. To improve the display quality, high‐quality micro/mini‐LED display pixels with fully enclosed composite micro/nano‐packages and in situ nanoimprint technology are proposed and demonstrated in this work. The nanoimprint template is designed as a composite structure comprising an intermediate sandwich cavity array and thin‐bottom nanostructure layer. Contact is maintained between the template and LED chips array substrate. By vacuuming the sealed sandwich cavities, the thin‐bottom nanostructure layer is deformed to drive the upward protrusion of the liquid optical polymer. Moreover, the nanocavities on the thin nanostructure layer are fully filled by the polymer, forming a composite micro/nano‐package. The characteristics of the composite micro/nano‐package, such as the aperture and protrusion height, can be flexibly adjusted by changing the template structure or process parameters. A 6 × 8 array LED chips display device enclosed by a composite micro/nanopackage is developed. The divergence angle of the single LED chip decreases to 72° from the original 138°, the light‐extraction efficiency increases18.4%, and the luminescence spectrum and current‐voltage characteristics changes only minimally.